Walking beam furnace

ABSTRACT

A furnace of the walking beam type in which the portion of the hearth located between two walking beams can be lifted above the level assumed by the walking beams during the feeding movement in order to permit the feed of the charge to be interrupted without the necessity for stopping the feeding movement of the beams.

United States Patent [1 1 Bengtsson WALKING BEAM FURNACE [75] Inventor: Ake Bengtsson, Huddinge, Sweden [73] Assignee: Aktiebolaget Tabougnar,

Stockholm, Sweden [22] Filed: Nov. 29, 1971 [21] Appl. No.: 202,814

[30] Foreign Application Priority Data [58] Field of Search. 263/6 A, 6 R; 198/219; 4.32/6, 432/9, 33, 34, 45, 122, 121; 34/151 [451 Feb. 19,1974

Primary Examiner-John .l. Camby Assistant Examiner-Henry C. ,Yuen Attorney, Agent, or Firm-Pierce, Scheffler & Parker [57] ABSTRACT A furnace of the walking beam type in which the portion of the hearth located between two walking beams can be lifted above the level assumed by the walking beams during the feeding movement in order to permit the feed of the charge to be interrupted without the necessity for stopping the feeding movement of 2 Claims, 1 Drawing Figure [5 6] References Cited UNITED STATES PATENTS 3,662,876 5/1972 Hollis 198/219 3,565,241 2/1971 Race 198/219 3,554,505 l/1971 Dessants ..432/122 the beams 3,567,198 3/1971 Gentry ..432/34- I13 mi l 11 1 WALKING BEAM FURNACE This invention relates to a walking beam furnace and its object is to produce a furnace at which the feed of the charges within some part of the furnace can be interrupted without requiring the feeding movements of the walking beams to be stopped. The invention is characterized in that the hearth portion located between two walking beams at least to a part of the furnace length can be lifted above the level assumed by the walking beams during the feeding movement. An embodiment of the invention is described in the following, with reference to the accompanying drawing showing a cross-section through a walking beam furnace without showing the roof or upper portion of the invention.

The walking beam furnace comprises a hearth zone 1 with walls 2, 3 and a roof (not shown). Beneath the hearth zone 1 a machine room 4 is located which includes the drive mechanisms 5 and 6 for the walking beams 7 and 8. The walking beams 7 and 8 can in a usual way carry out reciprocating movements such, that the beams in their forward movement are lifted to lift the charges 9 from the hearth plane. In the embodiment shown, the hearth comprises four longitudinal ridges 10, 11, 12 and 13, of which the ridges 10 and 11 are located each on one side of the walking beam 8 and the ridges 12 and 13 each on one side of the walking beam 7. The walking beams move forwards and rear wards and, respectively, upwards and downwards, with gaps between the sides of the ridges and the outsides of the walking beams. The drive mechanisms 5 and 6 for the walking beams are constructed in a conventional way and will not be described in greater detail in the present invention.

The two central ridges 11 and 12 located between the walking beams are according to the invention adapted to be lifted to a certain height above their normal position. The level said ridges are adapted to assume lies above the level, which the walking beams 7 and 8 can assume during their forward movement. When, thus, the ridges 11 and 12 have been lifted to their highest level, they thereby lift the charges supported thereon, so that the walking beams do not reach up to and cannot catch the charges, which thereby remain lying on the ridges 11 and 12 and are not advanced in the furnace. The ridges 11 and 12, i.e., the hearth between the walking beams, is formed so as to be liftable along the entire lengths of the furnace or along a part thereof, according to the effect desired. The hearth is lifted by means of a mechanism 14, which may include hydraulic pistons, beams or wheels against which the hearth rests. The operation of the liftable and lowerable hearth preferably is so controlled that the hearth is lifted immediately prior to or simultaneously with the lifting of the walking beams, and that the hearth is lowered as soon as the walking beams have been lowered.

Owing to the fact that the hearth, i.e., the ridges l1 and 12, are not lifted before the lifting of the beams has taken place, the charge 9 at the stay-time in a certain position in the furnace normally will abut the entire hearth and thereby be held straight. If the charge would rest only on the lifted ridges 11 and 12, this would involve the risk that the ends of the charge would be curved. It is to be observed, therefore, that the liftable and lowerable hearth is not a walking beam, but only performs an upward and downward movement without moving the charges forward in the furnace. The hearth having been lowered to the same level as the other ridges 10 and 13, the charge in a usual way will rest over the entire hearth and can be reached by the walking beams 7 and 8 for forward movement in the furnace. According to the desired stay-time in a certain place or position in the furnace, the liftable and lowerable hearth can be caused to perform a certain number of lifting and lowering movements, so that the walking beams at their feeding movements actuate only those charges, which are not affected by the liftable and lowerable hearth, i.e., those charges which are located before or behind the liftable and lowerable hearth portion.

It is possible, of course, to design the hearth such as to be liftable and lowerable along the entire hearth length, but this is generally not required, as it is particularly desired that the hearth in the preheating zone can be lifted between the walking beams and the charges here are given a longer stay-time.

What 1 claim is:

1. A walking beam furnace, which comprises an elongated oven hearth;

a pair of walking beams disposed at opposite sides of the hearth;

means for periodically raising said walking beams above the plane of the hearth and advancing them when raised, thereby effecting forward feeding movement of a charge supported thereon and thereafter retracting and lowering said walking beams to the plane of the hearth;

at least one portion of the hearth length located between said walking beams being vertically liftable; and

means for intermittently vertically lifting said liftable portion of the hearth, during the feeding movement of said walking beams, above the level assumed by the walking beams when lifted thereby raising but not forwardly feeding charge supported on said liftable portion.

2. A walking beam furnace according to claim 1, in which said lifting means is adapted to effect lifting of said hearth portion in connection with or immediately prior to the lifting of the walking beams. 

1. A walking beam furnace, which comprises an elongated oven hearth; a pair of walking beams disposed at opposite sides of the hearth; means for periodically raising said walking beams above the plane of the hearth and advancing them when raised, thereby effecting forward feeding movement of a charge supported thereon and thereafter retracting and lowering said walking beams to the plane of the hearth; at least one portion of the hearth length located between said walking beams being vertically liftable; and means for intermittently vertically lifting said liftable portion of the hearth, during the feeding movement of said walking beams, above the level assumed by the walking beams when lifted thereby raising but not forwardly feeding charge supported on said liftable portion.
 2. A walking beam furnace according to claim 1, in which said lifting means is adapted to effect lifting of said hearth portion in connection with or immediately prior to the lifting of the walking beams. 